Distillation of readily volatilizable



Oct. 15, 1935. F. JOHANNSEN 2,017,401

DISTILLATION OF READILY VOLA'IILIZABLE METALS Original Filed Feb. 2, 193a Patented 15, 1935 UNITED "STATES PATENT OFFICE I I DiSTIIJiATION OIZIZZJIE EI mm y.

Friedrich Johannsen,

Magdebnrg, Germany, as-

many

Original application February 2, 193:, Serial No.

Divided and this application October 12, 1933, Serial No. 693,372. In Germany Feb-s mar: 12, 1932 1 Claims. (01. ass-1a) The present invent on relates to the distillation of readily vola ble metals, such for example, as zinc or cadmium. It has already been proposed to carry out such a process in a muflie s built into a rotary furnace and mounted on the axis of rotation of the furnace: charging was effected at one end of the muflle. whilst discharge ofthe residue and removal of the metal vapours and reduction gases were eflected from the other l0- end of the muiile into a condenser. The residue was discharged from the condenser through an aperture provided for the purpose, but it has been found that a certain amount of the metal vapour condenses on the residue before its discharge and 15 is therefore lost, and it is one of the main objects of this invention to overcome this drawback.

"Ihe invention consists in apparatus for the distillation of readily volatllizable metals, such as 20 zinc, cadmium and the like, in one or more retorts in a rotating furnace, wherein the retort or retorts communicate at one end directly with a space in which one or more condensers is or are located parallel to the axis of rotation of the 25 furnace, spaces being left around the condenser or condensers to permit travel of the solid charge upon, rotation of the furnace, while the metal vapours pass into the condenser or condensers. Such a construction differs from that forming an the subject matter of the British Patent specification No. 374,900 and United States application Serial No. 580,990 owned by the assignee of the present application, owing to the fact that, according to the latter, communication between the 35 retort and the space surrounding the condenser is by means of a helical pipe instead of directly as in the present instance.

In order that theinvention may be more fully understood, two examples of apparatus are shown 40. diagrammatically in the accompanying drawing,

wherein:-

Flgure 1 is a longitudinal section through a rotary furnace with six retorts built into it,

Figure 2 is a cross-section corresponding to the 45 line A-B in Figure 1,

Figure 3 is a longitudinal section through a rotary furnace with six retorts and six condensers and Figure 4 is a cross-section of Figure 3 corre- 50 sponding to the line C-D.

In the following descriptiona zinc distilling process is referred to by way of example. In both examples of apparatus shown, I is the rotary furnace and 2 the zinc retorts, arranged parallel 55 to the axis of rotation of the furnace.

In the constructional form according to Figures 1 and 2 the charge passes from the bunker 4 through the worm 3 to an ante-chamber 20 which is in communication with six retorts 2, so

that the charge introduced enters into that one of the retorts which is at the bottom for the time being. In order to prevent any pronounced falling back of the charge from the'retorts when in the uppermost position retention plates-2| are provided. At the outlet end all the retorts 1 open into a commonchamber 22 in which the condenser 5 is so mounted that the charge passes to the discharge outlet 24 through an annular space 23 between the condenser and the walls of the chamber 22, whilst the zinc vapours enter the condenser 5 through the opening 6. The con-. denser is rigidly connected to the chamber 22 and to the furnace l and rotates together with the furnace. The residue is conducted from the outlet 24 into an annular chamber" in which there are arranged one or more shut-off devices, preferably in a .manner resembling sluices. The cooled residue leaves the annular chamber 25 through an outlet 26. The heating of the furnace is effected by a burner Ii which 25 projects through the hollow shaft of the worm 3. The gases of combustion play around the whole of the six retorts 2 and .pass at 21 into an annular chamber 21' which is left between the wall of the chamber 22 and the inner wall of the furnace: from this annular chamber 21' they are led into the furnace head 3i and through the pipe 52 to the outside. The residue and metal vapours both moving in the direction of the axis of rotation of the furnace, are removed from the reduction zone separately since withdrawal of the metal vapours takes place in the centrally situated condenser 5 and the residue is removed through the annular space 23 surrounding the condenser.

In apparatus according to Figures 3 and 4 the metal vapours begin to separate from the charge near the feeding end of the chamber 29, the type of furnace being otherwise similar to that shown in Figures 1 and 2. The charge, fed forward 4 from the bunker 4 by the worm 3,.falls at 28 into the chamber}! in which six separate condensers 5 are so arranged that the charge is thoroughly preheated, by the heat released during condensation, upon its way from the point of 50 admission along the'outside of the condensers 5 up to the point of admission'to the retorts 2. The removal of theyresidue may be effected very simply, since the ends of the retorts extend beyond the end of the furnace at. which the combusea tion gases are discharged and are closed for example by separate covers 30 which are opened periodically. The zinc vapours and reduction gases which are generated in the retorts 2 are drawn in a current contrary to the direction of travel of the material towards the condensers 5 and into them through orifices 6: the waste gases from the condensers are carried off at 1 and are discharged into a flue 8.

What I claim and desire to secure by Letters Patent of the United States is:-- -1. An apparatus for the distillation of readily volatilizable material such as zinc, cadmium, and the like, comprising a rotary furnace, a. retort disposed in said furnace for rotation therewith, a condenser mounted for rotation with said furnace and being at least partially disposed therein, means for feeding material to be distilled into said furnace and through said retort, means for conducting the distillation vapors into the condenser at a point-in said furnace where the condenser and the material being treated are above the temperature 'of condensation of said vapors, whereby precipitation of said vapor on said material is prevented, and means independent of saidcondenser for discharging the residue of the distillationprocess.

2. An apparatus for the distillation of readily volatilizable material such as'zinc, cadmium, and the like, comprising a rotary furnace, a retort disposed in said furnace for rotation therewith, a condenser mounted for rotation with said furnace and having its intake end disposed interiorly thereof, means for 'feeding material to be distilled through the furnace and for bringing said material into heat exchange contact with the condenser adjacent the intake end thereof, whereby substantially to equalize the temperature of the material and the condenser at that point and above the condaisation temperature of the vapor to prevent precipitation thereof upon the material, and means independent of the condenser for discharging the residue of the distillation process.

3. An apparatus for the distillation of readily volatilizable material such as zinc, cadmium, and the like, comprising a rotary furnace, a retort disposed in said furnace for rotation therewith, a condenser mounted for rotation with said furnace and having a portion of its length disposed interiorly thereof with its walls spaced from the walls of the furnace, means for feeding a charge of material into the furnace and into contact with the walls of the condenser to substantially equalize the temperaturev of the condenser and the material at that point, and means for conducting the distillation vapors into said condenser in a zone of the furnace where the material and the condenser are normally above the temperature of condensation of the vapor.

4. Apparatus for the distillation of readily volatilizable materials such as zinc, cadmium and the like, comprising in combination a rotary fur- 5 walls of said furnace to permit contact between said material and the outer, surface of said condenser to eifect an approximate equalization of temperature between said material and said condenser. 15

5. Apparatus for the distillation of readily volatilizable metals such as zinc, cadmium and the like, comprising in combination a rotary furnace, at least one retort in and rotating with said furnace communicating at one end with the in- 20 terior of said furnace, at least on'e condenser in and rotating withand spaced from the walls of said furnace, and means for feeding a charge of material into said retort and thence into contact with the outer surface of said condenser to effect 25 an approximate equalization of temperature between said material and said condenser, thereby to prevent the condensation of vapors on said material.

6. Apparatus for the distillation of readily 30;

volatilizable materials such as zinc, cadmium and the like, comprising in combination a rotary furnace, means for feeding a charge of material into said furnace, at least one retort in and rotating with said furnace, communicating at one end 5- with the interior of said furnace, at least one condenser projecting for a part of its length into the interior of said furnace, said condenser rotating with said furnace and spaced from the walls of said furnace to permit contact between 40 said material and the outer'surface of said condenser.

7. Apparatus for the distillation of readily volatilizable materials such as zinc, cadmium and the like, comprising in combination a rotary fur-. 45 nace, at least one retort in and rotating with said furnace, said retort having its inner end open to the interior of said furnace, means for feeding a charge of material into said furnace adjacent the outer end of said retort, at least one condenser 5 in and rotating with ,said furnace and spaced from the walls of said furnace to permit contact between the outer surface of said condenser and said material after said material has passed through said retort to effect approximate equali- 5 5- 

